1. Field of the Invention
The present invention relates to an image-processing method and system for reconstructing an image having a predetermined resolution, based on a stored image signal that has been subjected to a multiple-resolution transformation process, and performing a predetermined image-processing process on the reconstructed image, and relates to a computer readable storage medium recording a program which makes a computer execute the image-processing method.
2. Description of the Related Art
There have recently been proposed methods of performing a multiple-resolution transformation process on an image signal which represents an image acquired by an image reader, a digital still camera, etc., in order to obtain hierarchical data for each resolution level, which represents an image whose resolution becomes ½P times that of the resolution of the acquired image and whose size becomes ½2P times that of the acquired image. Each hierarchical data obtained is encoded, compressed and stored. It is also known that such multiple-resolution transformation processes utilize, for example, the wavelet-transformation utilized in JPEG 2000, the Laplacian pyramid-transformation utilized in the Flash Pix file (proposed by Eastman Kodak), or the Gaussian pyramid-transformation.
On the other hand, for cases in which an image based on an image signal that has been subjected to the multiple-resolution transformation process and stored, is output as a visible image to a CRT monitor, film, etc., the image is reconstructed and used at the same resolution level or image-size as the acquired image, or at an intermediate resolution level or different image-size (enlarged or reduced) than that of the acquired image, depending on the intended application of the image. Because of this, data transfer or image processing can be performed at the resolution level or image-size required for actual reproduction and output. Particularly, for cases in which the aforementioned image processing, etc., are performed on an acquired image whose image-size has been reduced to a smaller size and a lower resolution level, the operating speed and efficiency of the entire system are improved. For instance, for cases in which there is a need to reproduce a high-quality image, as in the case of printers, a high-quality image having the same resolution and image-size as the acquired image can be reproduced by reconstructing images, based on the hierarchical data of all levels which represent the images up to the maximum resolution. When reproducing an image whose resolution is not as high as that of an image output by a printer, as in the case of CRT monitors, an image with a lower resolution and a smaller image-size than that of the acquired image can be reproduced based on the hierarchical data representing the reduction image. Further, an image with a lower resolution and a smaller size than the acquired image but suitable for reproduction at the resolution and screen size of a CRT monitor can be reproduced by enlargement or reduction as necessary.
For cases in which, based on an image signal that has been subjected to the multiple-resolution transformation process and stored, an image with a different resolution level from the reference-resolution (normally, the reference-resolution is the resolution of the acquired image) is reconstructed, and a predetermined image-processing process is to be performed on the thus reconstructed image, the image signal representing the reconstructed image is input to an image-processing circuit and the image-processing is performed based on use of the image-processing parameter set in correlation with the aforementioned reference-resolution image (acquired image) having the aforementioned reference-resolution.
However, there are cases in which the set image-processing parameter is not always suitable for the reconstructed image. For instance, for cases in which the image-processing circuit performs a process of spatially correcting an image, such as a frequency enhancement process, a smoothing process, etc., the size of the processed image relative to the actual image varies depending upon image resolution. That is, the mask-size, for example, is dependent on image resolution. Because of this, if the aforementioned image-processing is performed on a reconstructed image based on use of a mask size (9×9 pixels)set for the reference-resolution image, an image component not included in processing the reference-resolution image will be contained within the mask when the reconstructed image is lower in resolution than the reference-resolution image, and an image component included in processing the reference-resolution image will not be contained within the mask when the reconstructed image is higher in resolution than the reference-resolution image. Consequently, that portion of the reconstructed image not equivalent spatially will be enhanced or smoothed, giving rise to the problem wherein the image characteristics of the reconstructed image subjected to the predetermined image-processing process are not the same as those of the reference-resolution image subjected to the predetermined image-processing. If the difference in resolution between the reference-resolution image and the reconstructed image becomes greater, this problem also becomes greater.
One method considered for solving the above problem is to archive an image-processing parameter corresponding to each resolution level in correlation with the archived image when encoding, compressing, and storing each hierarchical data (hereinafter also referred to as image-archiving time), for example. If an image-processing parameter corresponding to each resolution level is to be stored, however, the number of image-processing parameters will be enormous, and management of the image-processing parameters becomes extremely cumbersome. In addition, because image-processing parameters corresponding to all resolution levels must be calculated and stored at a stage wherein a determination as to whether or not they are actually to be utilized has not been made the aforementioned method is inefficient.